P-43. Molecular characterization and detection of Citrus yellow mosaic Badnavirus (CMBV) infecting Citrus sinensis L. osbeck (Sweet Orange)

Citrus yellow mosaic virus (CMBV) is a member of Badnavirus genus and family Caulimoviridae. Virus is a bacilliform particle measuring about 30 x 120 nm. The virus infects various citrus species and cultivars. This virus is also the causative of mosaic disease on sweet orange. Recent survey on virus prevalence in citrus growing parts of India was done and the most effective prevalence was found to be in Southern states of India, especially Andhra Pradesh. Virus disease symptoms include mosaic pattern on leaves, fruits and other branches of the plant. Virus is mostly graft transmitted in field conditions and also sap, mealy bug transmitted under experimental conditions. Sweet orange being mostly graft propagated this virus infection is most common in this cultivar due to use of infected budwood in grafting. This infected budwood serves as a major source of this virus spread to other parts of sweet orange belt in India. So there is a need for development of sensitive diagnostics for detection of this virus in budwood before grafting. We have developed a PCR assay and a Dot-blot assay for detection of this virus. A Primer pair was designed to amplify a 2.7 kbp fragment of the ORF3 of virus genome and PCR was standardized for the virus detection. The amplicon was cloned and sequenced. Sequence analyis with the other members of Badnavirus showed its close relationship to the Cacao swollen shoot virus (CSSV), a member of Badnavirus genus. The amplicon was used as probe in developing a radiolabelled Dot-blot assay for diagnosis of virus infected samples. These molecular tests developed are sensitive and could be used in virus detection from the infected field samples.